Enhanced Wellhead Clamp Type Hub Connection

ABSTRACT

An apparatus for connecting an upper wellhead member to a lower wellhead member includes a box connector. The box connector has an upper portion that selectively circumscribes the upper wellhead member and a lower portion that selectively circumscribes the lower wellhead member. An adapter plate assembly having an upper adapter ring selectively engages a hub profile of the lower wellhead member, and a separate lower adapter ring selectively engages a generally opposite facing lower hub profile of the lower wellhead member. A plurality of locking dog assemblies drive the adapter plate assembly into engagement with the hub profile and the lower hub profile, the locking dog assemblies being spaced around the box connector.

BACKGROUND

1. Field of the Disclosure

This invention relates in general to wellhead systems, and in particular, to an interface between an existing clamp/hub or flange connection with new equipment.

2. Description of Prior Art

Various components of wellhead systems are often connected together with a clamp and hub connection. A clamp and hub connection typically includes an outside profile on each of the mating ends of the wellhead components that are to be connected. These outside profiles act as the hub elements of the clamp and hub connection. The clamp is generally a radially outer member that engages the hub elements to secure the wellhead components together. Depending on the size and pressure rating of a clamp and hub connection, existing clamp and hub connections on wellhead systems usually have limited bending moment capacity. Modern well intervention equipment that is connected to the wellhead is often significantly heavier than the equipment which was originally installed on these connections. Therefore the addition of such modern equipment to the wellhead system could exceed the bending moment capacity of the original connection. The bending moment capacity of the connection can be increased by enlarging the size of the clamp, however this will not be a viable solution where available space around the wellhead system is limited.

SUMMARY OF THE DISCLOSURE

Methods and apparatus of the current disclosure can enhance the bending moment capacity of a clamp/hub and flange connection to allow installation of modern well intervention equipment, such as, for example, coil tubing units. In some instances where the clamp is identified as being the structurally weak point, relative to the hub elements, making the clamp and hub connection “clamp weak”, then embodiments of this disclosure can assist with increasing the pressure rating to provide greater flexibility in well workover operations. Embodiments of this disclosure can allow for new equipment to be added to older or existing platform developments where well side-tracks and re-drills encounter higher operating pressures and can also allow for the installation and operation of well intervention equipment which is much heavier than intended for the original well design.

In an embodiment of the system and method of the present disclosure, an apparatus for connecting an upper wellhead member to a lower wellhead member includes a box connector. The box connector has an upper portion that selectively circumscribes the upper wellhead member and a lower portion that selectively circumscribes the lower wellhead member. An adapter plate assembly having an upper adapter ring selectively engages a hub profile of the lower wellhead member, and a separate lower adapter ring selectively engages a generally opposite facing lower hub profile of the lower wellhead member. A plurality of locking dog assemblies drive the adapter plate assembly into engagement with the hub profile and the lower hub profile, the locking dog assemblies being spaced around the box connector.

In an alternate embodiment of this disclosure, an apparatus for connecting an upper wellhead member to a lower wellhead member includes a box connector. The box connector has an upper portion for selectively circumscribing the upper wellhead member and a lower portion for selectively circumscribing the lower wellhead member. An annular seal is located between the lower wellhead member and the upper wellhead member. An adapter plate assembly has an upper adapter ring and a lower adapter ring. A plurality of upper locking dog assemblies selectively engage the upper adapter ring to set the annular seal and a plurality of lower locking dogs selectively engage the lower adapter ring.

In yet another embodiment of the current disclosure, a method for connecting an upper wellhead member to a lower wellhead member includes disposing an adapter plate assembly on a lower hub profile of the lower wellhead member, the adapter plate assembly having an upper adapter ring and a separate lower adapter ring. A box connector is threaded onto an end of the upper wellhead member. The box connector has a plurality of locking dog assemblies spaced around the box connector and extending through a sidewall of the box connector. The upper wellhead member is landed onto the lower wellhead member so that a portion of the box connector circumscribes the lower wellhead member. The locking dog assemblies are actuated so that an end of each of the locking dog assemblies engage the adapter plate assembly, driving the upper adapter ring and lower adapter ring apart and into engagement with the lower wellhead member.

BRIEF DESCRIPTION OF THE DRAWINGS

Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a quarter sectional perspective view of an example of a wellhead assembly with a clamp hub connector in accordance with an embodiment of this disclosure.

FIG. 2 is a detailed cross sectional view of an example of the clamp hub connector of FIG. 1 showing an upper locking dog assembly.

FIG. 3 is a detailed cross sectional view of an example of the clamp hub connector of FIG. 1 showing a lower locking dog assembly.

FIG. 4 is a quarter sectional perspective view of an example of a wellhead assembly with a clamp hub connector in accordance with an embodiment of this disclosure.

FIG. 5 is a cross sectional view of an example of the wellhead assembly of FIG. 4 with the adapter plate assembly of the clamp hub connector mounted on the lower wellhead member, before the box connector is landed.

FIG. 6 is a perspective view of an example of an adapter plate assembly in accordance with an embodiment of this disclosure, with a quarter section of the upper adapter ring cutout.

FIG. 7 is a quarter sectional view of an example of a box connector with locking dog assemblies in accordance with an embodiment of this disclosure.

FIG. 8 is a quarter sectional perspective view of an example of a wellhead assembly with a flange connection in accordance with an embodiment of this disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The methods and systems of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments are shown. The methods and systems of the present disclosure may be in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey its scope to those skilled in the art. Like numbers refer to like elements throughout.

It is to be further understood that the scope of the present disclosure is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation.

Referring to FIGS. 1, 4, 5 and 8, wellhead assembly 10 includes upper wellhead member 12 and lower wellhead member 14. Wellhead assembly 10 can be, for example, a standard wellhead assembly, multibowl wellhead assembly, unitized wellhead assembly, or other type of wellhead assembly. Upper wellhead member 12 can be, for example, a multibowl wellhead and lower wellhead member 14 (usually existing equipment installed) can be, for example, a main wellhead body. Wellhead assembly 10 can be a surface wellhead located above a hydrocarbon production well.

Wellhead assembly 10 has a central wellhead bore 16. A hanger 18 or other tubular member can be located in the wellhead bore 16. Hanger 18 can support inner tubular members 20 such as production tubing, casing, unfinished pipe or other tubing within wellhead assembly 10. Packoff 22 seals the annular space between an inner cylindrical wall of lower wellhead member 14 and an outer cylindrical surface of hanger 18. Packoff 22 is an annular member with upper and lower ring shaped seals on both the inner diameter and outer surface of packoff 22. Packoff 22 has a test port 23 extending from its outer surface to its inner diameter. The test port 23 is located between the upper and lower annular seals so that both the upper seals and the lower seals can be pressure tested.

Lower wellhead member 14 has lower hub profile 24. Lower hub profile 24 has a generally upward facing radial surface that is defined by a reduction in the outer diameter of lower wellhead member 14. Lower hub profile 24 can include one or more planar surfaces that are concentric about central axis 26 or can curve upwards from its outer diameter towards central axis 26. An upper end of lower wellhead member 14 projects radially outward to define hub profile 28 on its lower surface that faces in a generally opposite axial direction than lower hub profile 24. Hub profile 28 has a generally downward facing surface and can be normal to central axis 26 or angled relative to central axis 26. A generally vertical outer diameter surface of lower wellhead member 14 connects the inner diameter of hub profile 28 and the inner diameter of lower hub profile 24.

Connector assembly 30 connects upper wellhead member 12 to lower wellhead member 14. Connector assembly 30 includes adapter plate assembly 32. In the example of FIG. 6, adapter plate assembly 32 is annular and includes an upper adapter ring 34 and a lower adapter ring 36. Both upper adapter ring 34 and lower adapter ring 36 are shown as split rings. Upper adapter ring 34 has an annular groove on its bottom surface that opens downward. Lower adapter ring 36 has a corresponding vertically extending lip on its top surface for engaging the annular groove of upper adapter ring 34. In an example, when upper adapter ring 34 is assembled with lower adapter ring 36, upper adapter ring 34 rests on lower adapter ring 36 with the vertically extending lip of lower adapter ring 36 engaged within the annular groove of upper adapter ring 34 and the split rings of lower adapter ring 36 and upper adapter ring 34 are arranged so that the splits between the rings do not coincide. For example, as shown in FIG. 6, the split rings of upper adapter ring 34 are rotationally offset by approximately 90 degrees from the split rings of lower adapter ring 36.

Looking now at FIGS. 1-6 and 8, in cross section, upper adapter ring 34 has a generally planar top surface that is perpendicular to central axis 26. Upper adapter ring 34 has a generally upward facing adapter shoulder 38 for mating with hub profile 28. In an example, the shape and size of adapter shoulder 38 is selected to correspond to the size and shape of hub profile 28 for the particular lower wellhead member 14 to which the upper wellhead member 12 will be connected. Adapter shoulder 38 can be located on a radially inward portion of upper adapter ring 34 (FIGS. 1-6) or can make up the top surface of upper adapter ring 34 (FIG. 8). Upper adapter ring 34 also has a generally downward sloped surface 40 for mating with a locking dog assembly 42. For the sake of clarity in the figures, each locking dog assembly 42 includes an actuation screw 50 and a dog nose 52. Surface 40 is located on a radially outward portion of upper adapter ring 34.

In cross section, lower adapter ring 36 has downward facing bottom surface 44 for engaging lower hub profile 24. Bottom surface 44 can include one or more planar surfaces that are concentric about central axis 26, or can curve upwards from its outer diameter towards central axis 26 in order to have a shape that corresponds to the shape of lower hub profile 24. Lower adapter ring 36 also has a generally upward sloped surface 46 for mating with a locking dog assembly 42. Surface 46 is located on a radially outward portion of lower adapter ring 36.

Connector assembly 30 also includes a box connector 48. Box connector 48 is shown as a single member having a ring like shape with an upper portion for selectively circumscribing upper wellhead member 12 and a lower portion for selectively circumscribing lower wellhead member 14. Box connector 48 has internal threads on an inner circumference for selective mating with external threads of upper wellhead member 12. The inner circumference of the upper portion of box connector 48 is sized to threadingly connect to upper wellhead member 12 and the inner circumference of the lower portion of upper wellhead member 12 is sized so that a seal ring located between the upper wellhead member 12 and lower wellhead member 14 can seal between the lower portion of upper wellhead member 12 and lower wellhead member 14.

A plurality of locking dog assemblies 42 are spaced around box connector 48 for driving adapter plate assembly 32 into engagement with lower wellhead member 14. Locking dog assemblies 42 extend radially through a sidewall of box connector 48. Each locking dog assembly 42 includes an actuation screw 50 and a dog nose 52. Dog nose 52 is located at a radially inner end of actuation screw 50. Locking dog assembly 42 has a profile on a radially outward end for actuating the locking dog assembly 42. In the embodiments of FIGS. 1-4 and 7, actuation screw 50 has external threads for mating with internal threads of a bore that extends radially through the sidewall of box connector 48. The profile on the radially outward end of actuation screw 50 can be, for example, a hex profile for receiving a hex tool to rotate actuation screw 50 and move locking dog assembly 42 radially inward through the sidewall of box connector 48. Alternately, other means for actuating locking dog assemblies 42 as known in the art may be provided.

Dog nose 52 can have a generally trapezoidal cross section with a radially outer profile, such as a lip, for engaging a radially inner profiled end of actuation screw 50. Each dog nose 52 is located between two other dog noses 52 so that together, the plurality of dog noses 52 define a multi-split adapter ring (FIG. 7). An upper sloped surface 54 of dog nose 52 can engage the generally downward sloped surface 40 of upper adapter ring 34 and a lower sloped surface 55 of dog nose 52 can engage the generally upward sloped surface 46 of lower adapter ring 36. Certain of the locking dog assemblies 42 can be upper locking dog assemblies that are axially located in box connector 48 so that dog nose 52 engages upper adapter ring 34. Other of the locking dog assemblies 42 can be lower locking dog assemblies that are axially located in box connector 48 so that dog nose 52 engages lower adapter ring 36. The upper locking dog assemblies are located axially higher in the sidewall of box connector 48 than the lower locking dog assemblies.

In an example of operation, connector assembly 30 can be used to connect upper wellhead member 12 to lower wellhead member 14. On an existing wellhead assembly, the upper wellhead member is removed from lower wellhead member 14. The original packoff can be replaced with packoff 22 and any existing hold-down set screw assemblies that were related to the original packoff and might interfere with connector assembly 30 can be blanked off, for example with plugs 56. As shown in FIG. 2, adapter plate assembly 32 can then be wrapped around lower wellhead member 14 and placed on lower hub profile 24, with the splits of upper adapter ring 34 and lower adapter ring 36 being offset from each other. Annular seal 58 can be located at an upper surface of lower wellhead member 14. Annular seal 58 can be a “T” shaped seal and located at a radially inner edge of the upper surface of lower wellhead member 14 (FIGS. 1-5). Alternately, annular seal 58 can be an o-ring or gasket type seal and located proximate to the radially inner edge of the upper surface of lower wellhead member 14 (FIG. 8).

Box connector 48 with locking dog assemblies 42 can be threaded onto the lower end of upper wellhead member 12. Alternately, box connector 48 can be secured to a lower end of upper wellhead member 12 by other known means. Retaining member 60 can be attached to box connector 48 to retain box connector 48 on upper wellhead member 12 and prevent relative axial movement between box connector 48 and the upper wellhead member 12 due to box connector 48 unthreading from upper wellhead member 12. Retaining member 60 can be a split ring that is screwed onto a top surface of box connector 48. The split ring can have an inner edge that engages a circular outer groove in upper wellhead member 12.

Upper wellhead member 12 can then be landed on lower wellhead member 14. The locking dog assemblies 42 located in the box connector 48 as upper locking dog assemblies can be actuated to engage upper adapter ring 34. As an example, there can be a total of twenty six locking dog assemblies 42, with sixteen being located in box connector 48 as upper locking dog assemblies and ten being located in box connector as lower locking dog assemblies. Upper locking dog assemblies can be actuated by threading actuation screw 50 into the sidewall of box connector 48 with a tool that engages the profile on the radially outward end of actuation screw 50. As upper sloped surface 54 of dog nose 52 engages the generally downward sloped surface 40 of upper adapter ring 34, upper adapter ring 34 will be driven radially inward and axially upward and into engagement with lower wellhead member 14 so that adapter shoulder 38 of upper adapter ring 34 mates with hub profile 28. This in turn will draw upper wellhead member 12 towards lower wellhead member 14, setting and energizing annular seal 58. Drawing lower wellhead member 14 and upper wellhead member 12 together can also cause movement of radially inward energizing members to set internal seals within wellhead assembly 10. For example, testable metal-to-metal seal assembly 62 adjacent to hanger 18 can be set by the upper wellhead member 12 being fixed into position.

The locking dog assemblies 42 located in the box connector 48 as lower locking dog assemblies can be actuated to engage lower adapter ring 36. Lower locking dog assemblies can be actuated by threading actuation screw 50 into the sidewall of-box connector 48 with a tool that engages the profile on the radially outward end of actuation screw 50. As lower sloped surface 55 of dog nose 52 engages the generally upward sloped surface 46 of lower adapter ring 36, lower adapter ring 36 will be driven radially inward and axially downward and into engagement with lower wellhead member 14 so that bottom surface 44 of lower adapter ring 36 mates with lower hub profile 24. The mating of bottom surface 44 of lower adapter ring 36 with lower hub profile 24 allows for the transfer of a bending moment from upper wellhead member 12 to lower wellhead member 14 through connector assembly 30. Because the axial length of lower wellhead member 14 that is located within and circumscribed by box connector 48, known as the swallow, will generally be greater than the swallow of the original connector, connector assembly 30 can provide an increased bending moment capacity over the original connector.

Methods and apparatus of the current disclosure can in this way improve the bending moment capacity of a clamp and hub connection compared to an existing connection. Embodiments of the current disclosure utilize the existing hub profile 28 and lower hub profile 24, minimizing the amount of work-over on lower wellhead member 14 required to install connector assembly 30 and provide such an increase in bending moment capacity. This allows for installation of modern well intervention equipment or other new wellhead members which are heavier than what was originally intended for use with the original well design.

The terms “vertical”, “horizontal”, “upward”, “downward”, “above”, and “below” are used herein only for convenience because elements of embodiments of this disclosure may be utilized in various positions.

The system and method described herein, therefore, are well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the system and method has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the system and method disclosed herein and the scope of the appended claims. 

What is claimed is:
 1. An apparatus for connecting an upper wellhead member to a lower wellhead member, the apparatus comprising: a box connector, the box connector having an upper portion that selectively circumscribes the upper wellhead member and a lower portion that selectively circumscribes the lower wellhead member; an adapter plate assembly comprising an upper adapter ring that selectively engages a hub profile of the lower wellhead member, and a separate lower adapter ring that selectively engages a generally opposite facing lower hub profile of the lower wellhead member; and a plurality of locking dog assemblies for driving the adapter plate assembly into engagement with the hub profile and the lower hub profile, the locking dog assemblies being spaced around the box connector.
 2. The apparatus of claim 1, wherein certain of the locking dog assemblies engage the upper adapter ring and other of the locking dog assemblies engage the lower adapter ring.
 3. The apparatus of claim 1, wherein the locking dog assemblies extend radially through a sidewall of the box connector, the locking dog assemblies having a profile on a radially outward end for actuating the locking dog assemblies.
 4. The apparatus of claim 1, wherein the upper adapter ring has a generally upward facing adapter shoulder that engages the hub profile for selectively drawing the upper wellhead member towards the lower wellhead member for setting an annular seal located between the lower wellhead member and the upper wellhead member.
 5. The apparatus of claim 1, wherein the locking dog assemblies include an actuation screw and a dog nose located at a radially inner end of the actuation screw that selectively engages and urges one of the adapter rings radially inward, wherein the actuation screw has external threads for mating with internal threads of a bore that extends radially through a sidewall of the box connector.
 6. The apparatus of claim 1, wherein the box connector has internal threads on an inner circumference for selective mating with external threads of the upper wellhead member.
 7. The apparatus of claim 1, further comprising a retaining member attached to the box connector for selectively retaining the box connector on the upper wellhead member.
 8. An apparatus for connecting an upper wellhead member to a lower wellhead member, the apparatus comprising: a box connector, the box connector having an upper portion for selectively circumscribing the upper wellhead member and a lower portion for selectively circumscribing the lower wellhead member; an annular seal located between the lower wellhead member and the upper wellhead member; an adapter plate assembly, the adapter plate assembly having an upper adapter ring and a lower adapter ring; a plurality of upper locking dog assemblies, the upper locking dog assemblies selectively engaging the upper adapter ring to set the annular seal; and a plurality of lower locking dogs, the lower locking dog assemblies selectively engaging the lower adapter ring.
 9. The apparatus of claim 8, wherein the locking dog assemblies extend radially through a sidewall of the box connector, each of the locking dog assemblies having an actuation screw and a dog nose located at a radially inner end of the actuation screw, wherein the actuation screw is threadingly connected to the sidewall of the box connector and the dog nose engages the adapter plate assembly.
 10. The apparatus of claim 8, wherein the upper adapter ring has a generally upward facing adapter shoulder that engages a hub profile of the lower wellhead member for selectively drawing the lower wellhead member and upper wellhead member together for setting the annular seal.
 11. The apparatus of claim 8, wherein the lower adapter ring has a bottom surface that engages the lower hub profile for selectively transferring a bending moment from the upper wellhead member to the lower wellhead member.
 12. A method for connecting an upper wellhead member to a lower wellhead member, the method comprising: disposing an adapter plate assembly on a lower hub profile of the lower wellhead member, the adapter plate assembly having an upper adapter ring and a separate lower adapter ring; threading a box connector onto an end of the upper wellhead member, the box connector having a plurality of locking dog assemblies spaced around the box connector and extending through a sidewall of the box connector; landing the upper wellhead member onto the lower wellhead member so that a portion of the box connector circumscribes the lower wellhead member; and actuating the locking dog assemblies so that an end of each of the locking dog assemblies engage the adapter plate assembly, driving the upper adapter ring and lower adapter ring apart and into engagement with the lower wellhead member.
 13. The method of claim 12, wherein the step of driving the upper adapter ring and lower adapter ring apart and into engagement with the lower wellhead member includes driving the upper adapter ring into engagement with a hub profile of the lower wellhead member and driving the lower adapter ring into engagement with the lower hub profile.
 14. The method of claim 12, wherein the locking dog assemblies have external threads and the step of actuating the locking dog assemblies includes rotating the locking dog assemblies to move the locking dog assemblies axially inward through the sidewall of the box connector.
 15. The method of claim 12, wherein each of the locking dog assemblies include an actuation screw and a dog nose located at a radially inner end of the actuation screw, and wherein the step of actuating the locking dog assemblies includes threading the actuation screw into the sidewall of the box connector so that the dog nose engages the adapter plate assembly.
 16. The method of claim 12, wherein the step of actuating the locking dog assemblies includes actuating certain of the locking dog assemblies so that the adapter plate assembly engages a hub profile of the lower wellhead member and actuating other of the locking dog assemblies so that the adapter assembly engages a lower hub profile of the lower wellhead member, the lower hub profile facing in a generally opposite direction than the hub profile.
 17. The method of claim 12, further comprising before landing the upper wellhead member onto the lower wellhead member, locating an annular seal between the upper wellhead member and the lower wellhead member.
 18. The method of claim 17, wherein the adapter plate assembly has an upper adapter ring and wherein the step of driving the adapter plate assembly into engagement with the upper wellhead member includes driving the upper adapter ring into engagement with a hub profile of the lower wellhead member to energize the annular seal.
 19. The method of claim 12, wherein the step of actuating the locking dog assemblies includes driving the adapter plate assembly axially with the locking dog assemblies to energize an annular seal between the upper wellhead member and the lower wellhead member.
 20. The method of claim 12, further comprising after threading the box connector onto the end of the upper wellhead member, attaching a retaining member to the box connector, the retaining member engaging the upper wellhead member to prevent relative axial movement between the box connector and the upper wellhead member. 